Motor control device and method for controlling motor control device

Abstract

Provided are a motor control device and a method for controlling a motor control device. Harmonics of an input current may be reduced by adjusting an output of an inverter.

What is claimed is: 
     
       1. A motor control device comprising:
 an input unit that rectifies an external AC power into DC power; 
 a smoothing circuit to smooth the rectified DC power; 
 an inverter that converts the smoothed DC power into AC power and outputs the converted AC power to a motor; and 
 a controller that controls a switching operation of the inverter to compensate for harmonics at the input unit, 
 wherein the controller detects a voltage at the smoothing circuit and an output current of the inverter, calculates a compensation value that corresponds to a harmonic component in an output of the inverter based on the detected voltage at the smoothing circuit and the output current of the inverter, and controls the switching operation of the inverter to compensate for harmonics at the input unit by adjusting the output of the inverter based on the detected voltage of the smoothing circuit and the output current of the inverter to reflect the compensation value, 
 wherein the compensation value includes a waveform, a magnitude, and a phase corresponding to the harmonic component in the output of the inverter, 
 wherein, when the controller calculates the compensation value, the controller further extracts a harmonic component from the voltage at the smoothing circuit, calculates an output magnitude of the inverter based on the output current of the inverter, calculates the compensation value further based on the extracted harmonic component from the voltage at the smoothing circuit, and determines the magnitude of the compensation value based on the output magnitude of the inverter, 
 wherein the controller further adjusts the output of the inverter according to the harmonic component extracted from the voltage at the smoothing circuit and the output magnitude of the inverter, and 
 wherein the output of the inverter that is compensated for harmonics is detected as a waveform in which maximum and minimum peak values are reduced a prescribed amount relative to a waveform of the output before compensating for harmonics. 
 
     
     
       2. The motor control device of  claim 1 , wherein the smoothing circuit does not include an LC resonant circuit. 
     
     
       3. The motor control device of  claim 2 , wherein the smoothing circuit does not include a reactor between the input unit and the inverter. 
     
     
       4. The motor control device of  claim 1 , wherein the smoothing circuit is a film capacitor. 
     
     
       5. The motor control device of  claim 1 , wherein the controller further calculates the compensation value for adjusting the output of the inverter based on the output magnitude. 
     
     
       6. The motor control device of  claim 5 ,
 wherein the controller determines the waveform of the compensation value based on the extracted harmonic component. 
 
     
     
       7. The motor control device of  claim 6 , wherein the controller detects an input voltage input to the input unit, detects a phase of the input voltage and determines the phase of the compensation value based on the phase of the input voltage. 
     
     
       8. The motor control device of  claim 5 , wherein the controller adjusts the output of the inverter by controlling a switching operation of the inverter such that the compensation value is reflected in the output of the inverter. 
     
     
       9. A method for controlling a motor control device including an input unit that receives external AC power, a rectifier that rectifies the external AC power into DC power, a smoothing circuit to smooth the rectified DC power, and an inverter that converts the smoothed DC power into AC power for output to a motor, the method comprising:
 detecting a voltage at the smoothing circuit and detecting an output current of the inverter; 
 calculating a compensation value that corresponds to a harmonic component in an output of the inverter based on the detected voltage of the smoothing circuit and the output current of the inverter; and 
 adjusting the output of the inverter by controlling a switching operation of the inverter such that the compensation value is reflected in the output of the inverter, 
 wherein the compensation value includes a waveform, a magnitude and a phase corresponding to the harmonic component at the output of the inverter, 
 wherein calculating the compensation value includes:
 extracting a harmonic component from the voltage at the smoothing circuit and determining the waveform of the compensation value according to the extracted harmonic component; and 
 calculating an output magnitude of the inverter based on the output current of the inverter and determining a magnitude of the compensation value based on the output magnitude of the inverter, 
 wherein adjusting the output of the inverter includes reducing the output of the inverter by an amount corresponding to harmonics of the input current at the input unit, and 
 wherein an output current at the inverter with reduced harmonics is detected as a waveform in which maximum and minimum peak values are reduced a prescribed amount relative to a waveform of the output before harmonics are reduced. 
 
 
     
     
       10. The motor control device of  claim 9 , wherein the smoothing circuit does not include an LC resonant circuit. 
     
     
       11. The motor control device of  claim 10 , wherein the smoothing circuit does not include a reactor between the input unit and the inverter. 
     
     
       12. The method of  claim 9 , wherein the smoothing circuit is a film capacitor. 
     
     
       13. The method of  claim 9 , wherein detecting the voltage of the smoothing circuit and the output current of the inverter includes:
 first detecting the voltage of the smoothing circuit; and 
 detecting the output current of the inverter after detecting the voltage of the smoothing circuit. 
 
     
     
       14. The method of  claim 13 , further comprising:
 detecting an input voltage at the input unit. 
 
     
     
       15. The method of  claim 14 , wherein calculating the output magnitude of the inverter further includes:
 detecting a phase of the input voltage; and 
 determining the phase of the compensation value based on the phase of the input voltage. 
 
     
     
       16. A motor control device comprising:
 a rectifier circuit that converts received alternating current (AC) power into direct current (DC) power; 
 a capacitor that is positioned in parallel to rectifier circuit to smooth the converted DC power; 
 an inverter that converts the smoothed DC power into AC power and outputs the converted AC power to a motor; and 
 a controller that controls a switching operation of the inverter to compensate for harmonics at the rectifier circuit, 
 wherein the controller, when controlling the switching operation of the inverter to compensate for harmonics at the rectifier circuit, detects a voltage at the capacitor and an output current of the inverter, calculates a compensation value that corresponds to a harmonic component in an output of the inverter based on the detected voltage at the capacitor and the output current of the inverter, and adjusts the output of the inverter according to the harmonic component in an output of the inverter and the output current of the inverter to reflect the compensation value, 
 wherein the compensation value includes a waveform, a magnitude and a phase corresponding to the harmonic component in the output of the inverter, 
 wherein when the controller calculates the compensation value, the controller extracts a harmonic component from the voltage at the capacitor, further calculates the compensation value based on the harmonic component extracted from the voltage at the capacitor, calculates an output magnitude of the inverter based on the output current of the inverter, and determines the magnitude of the compensation value based on the output magnitude of the inverter, and 
 wherein the output of the inverter that is compensated for harmonics is detected as a waveform in which maximum and minimum peak values are reduced a prescribed amount relative to a waveform of the output before compensating for harmonics. 
 
     
     
       17. The motor control device of  claim 16 , wherein the controller further calculates the compensation value for adjusting the output of the inverter based on the output magnitude. 
     
     
       18. The motor control device of  claim 17 ,
 wherein the controller further determines the waveform of the compensation value based on the harmonic component extracted from the voltage at the capacitor. 
 
     
     
       19. The motor control device of  claim 18 , wherein
 the controller further detects an input voltage input to the input unit, detects a phase of the input voltage and determines the phase of the compensation value based on the phase of the input voltage. 
 
     
     
       20. The motor control device of  claim 17 , wherein the controller further adjusts the output of the inverter by controlling a switching operation of the inverter such that the compensation value is reflected in the output of the inverter.